Coupled-channels analyses for Li-9,Li-11 + Pb-208 fusion reactions with multi-neutron transfer couplings

Abstract

We discuss the role of two-neutron transfer processes in the fusion reaction of the Li-9,Li-11 + Pb-208 systems. We first analyze the Li-9 + Pb-208 reaction by taking into account the coupling to the Li-7 + Pb-210 channel. To this end, we assume that two neutrons are directly transferred to a single effective channel in Pb-210 and solve the coupled-channels equations with the two channels. By adjusting the coupling strength and the effective Q-value, we successfully reproduce the experimental fusion cross sections for this system. We then analyze the Li-11 + Pb-208 reaction in a similar manner, that is, by taking into account three effective channels with Li-11 + (208)pb, Li-9 + (210)pb , and Li-7 + (212)pb partitions. In order to take into account the halo structure of the Li-11 nucleus, we construct the potential between Li-11 and Pb-208 with a double folding procedure, while we employ a Woods-Saxon type potential with the global Akyuz-Winther parameters for the other channels. Our calculation indicates that the multiple two-neutron transfer process plays a crucial role in the Li-11 + Pb-208 fusion reaction at energies around the Coulomb barrier. (C) 2018 The Authors. Published by Elsevier B.V.